This invention relates generally to a weightlifting machine and, more particularly, to a weightlifting machine capable of providing a user with more weight while performing an eccentric muscle exercise than a concentric muscle exercise.
A strength building weightlifting exercise may include both concentric and eccentric muscle contractions. A concentric muscle contraction, or positive contraction, shortens a muscle as it acts against a resistive force, such as a weight. An eccentric muscle contraction, or negative contraction, lengthens a muscle while producing force. For example, during a bicep curl, a user performs a concentric muscle contraction to lift the weight upward and an eccentric muscle contraction while a user slowly lowers the weight back down from the lifted position. Essentially, an eccentric muscle contraction slows the descent of a weight instead of letting gravity completely pull the weight.
Eccentric muscle contractions generate more force than concentric muscle contractions. In addition, users can build greater strength by including eccentric muscle contraction exercises into a workout. Because of these two factors, users looking to quickly and effectively add strength may focus their workout around eccentric muscle contraction exercises.
Negative training focuses on eccentric exercises during a weightlifting workout. Negative training involves the use of heavier weights, which a user may not actually be able to lift concentrically, and the user exercises by only performing eccentric exercises.
Negative training using free weights is not without downsides. For example, negative training merely using free weights poses a higher risk for injury because heavier weights may be used. In addition, in many negative training exercises using free weights, a user needs a spotter to assist them while they exercise. The spotter helps the user move the heavy weights to a position where the eccentric exercise begins. For example, in the bicep curl example, the spotter assists the user to lift the heavy weights to the curled position, and then spot the user as the user slowly lowers the weights downward.
Negative training poses issues for users using conventional weightlifting machines. Generally, weightlifting machines require a user to select an amount of weight to lift prior to beginning an exercise. Conventional exercise equipment includes only one weight selection, so the amount a user selects is the amount of weight the user lifts during both the concentric and eccentric phases. A spotter could be used like the free weight example above to perform negative training, but people frequently use conventional exercise equipment for the very purpose of exercising alone without fear of injury.
The present invention is directed to overcoming one or more of the problems set forth above.